This invention relates generally to filter devices for filtering particulate from a fluid flow stream such as a water supply for use in an irrigation system. More particularly, this invention relates to an improved filter device of the type having a filter element adapted for automatic backwashing or flushing of accumulated particulate therefrom in response to cyclic on-off supply of the fluid flow stream.
Water filters are used in a wide range of different applications to collect and remove particulate matter from a water flow stream. In one specific application, water filters are employed in irrigation systems to filter out fine particulate and debris which may be present in a water supply, to prevent such particulate from passing to sprinkler heads or to low flow emitter devices where it can obstruct or otherwise interfere with the delivery of irrigation water at selected rates to surrounding vegetation. Such filters have typically included a filter medium designed to collect particulate of a target fine mesh size, wherein the pressure drop across the filter medium is directly proportional to the quantity of particulate collected thereon. Since an excessive pressure drop across the filter medium can significantly reduce water flow and thereby adversely impact the performance of the irrigation system, the filter medium must be periodically changed or appropriately backwashed or flushed to clean the accumulated particulate therefrom.
In the past, changing or cleaning of the filter medium has generally required manual intervention to access and expose the filter medium. Alternately, backwash flow valves and the like have been provided for manual operation to flush water in a reverse direction through the filter medium to flush collected particulate to a waste or drain site. Attempts to automate this process, such as by operating backwash devices in response to detected pressure drop across the filter medium, have been relatively complicated in design and operation and thus have not met with any significant degree of commercial acceptance.
There exists, therefore, a continuing need for further improvements in and to fluid filter devices of the type having a filter medium or filter element adapted for automated self-cleaning operation in a relatively simple and reliable manner. The present invention fulfills these needs and provides further related advantages.